I agree with Dan. I'd rather have two endpoints instead of needing an
option that changes the behavior entirely in the same route. I don't think
that a `preplan` route would be too bad.
On Wed, Jan 31, 2024 at 9:51 AM Daniel Weeks <dwe...@apache.org> wrote:
> I agree with the opaque tokens.
>
> However, I'm concerned we're overloading the endpoint two perform two
> distinctly different operations: distribute a plan and scan a plan.
>
> Changing the task-type then changes the behavior and the result. I feel
> it would be more straightforward to separate the distribute and scan
> endpoints. Then clients can call the scan directly if they do not know how
> to distribute and the behavior is clear from the REST Specification.
>
> -Dan
>
> On Tue, Jan 30, 2024 at 9:09 PM Jack Ye <yezhao...@gmail.com> wrote:
>
>> +1 for having the opaque plan tasks, that's probably the most flexible
>> way forward. And let's call them *plan tasks* going forward to
>> standardize the terminology.
>>
>> I think the name of the APIs can be determined based on the actual API
>> shape. For example, if we centralize these 2 plan and pre-plan actions to a
>> single API endpoint but just requesting different task types:
>>
>>
>> *pre-plan: POST /v1/namespaces/ns/tables/t/plan*{ "filter": { "type":
>> "in", "term": "x", "values": [1, 2, 3] }, "select": ["x", "a.b"],
>> "task-type": "plan-task" }
>>
>> { "plan-tasks": [ { ... }, { ... } ] }
>>
>>
>> *plan without a plan-task: POST /v1/namespaces/ns/tables/t/plan*{
>> "filter": {"type": "in", "term": "x", "values": [1, 2, 3] }, "select":
>> ["x", "a.b"], "task-type": "file-scan-task" } // file-scan-task should be
>> the default type
>>
>> { "file-scan-tasks": [ { ... }, { ... } ] }
>>
>>
>> *plan with a plan-task: POST /v1/namespaces/ns/tables/t/plan*{ "filter":
>> {"type": "in", "term": "x", "values": [1, 2, 3] }, "select": ["x", "a.b"],
>> "task-type": "file-scan-task", "plan-task": { ... } }
>>
>> { "file-scan-tasks": [...] }
>>
>> In this model, we just have a single API, and we can call it something
>> like PlanTable or PlanTableScan.
>>
>> What do you think?
>>
>> -Jack
>>
>>
>> On Mon, Jan 29, 2024 at 6:17 PM Renjie Liu <liurenjie2...@gmail.com>
>> wrote:
>>
>>> But to move forward, I think we should go with the option that preserves
>>>> flexibility. I think the spec should state that plan tasks (if we call them
>>>> that) are a JSON object that should be sent as-is back to the REST service
>>>> to be used.
>>>
>>>
>>> +1 for this.
>>>
>>> > One more thing that I would also change is that I don't think the
>>> "plan" and "scan" endpoints make much sense. We refer to the "scan" portion
>>> of this as "planFiles" in the reference implementation, and "scan" is used
>>> for actually reading data. To be less confusing, I think that file scan
>>> tasks should be returned by a "plan" endpoint and the manifest plan tasks
>>> (or shards) should be returned by a "pre-plan" endpoint. Does anyone else
>>> like the names "pre-plan" and "plan" better?
>>>
>>> I agree that "scan" may be quite confusing since it's actually planning
>>> file scan. Another options I can provide is: "plan" -> "plan-table-scan",
>>> "scan" -> "plan-file-scan"
>>>
>>>
>>>
>>>
>>> On Tue, Jan 30, 2024 at 9:03 AM Ryan Blue <b...@tabular.io> wrote:
>>>
>>>> As you noted the main point we still need to decide on is whether to
>>>> have a standard "shard" definition (e.g. manifest plan task) or to allow it
>>>> to be opaque and specific to catalogs implementing the protocol. I've not
>>>> replied because I keep coming back to this decision and I'm not sure
>>>> whether the advantage is being clear about how it works (being explicit) or
>>>> allowing implementations to differ (opaque). I'm skeptical that there will
>>>> be other strategies.
>>>>
>>>> But to move forward, I think we should go with the option that
>>>> preserves flexibility. I think the spec should state that plan tasks (if we
>>>> call them that) are a JSON object that should be sent as-is back to the
>>>> REST service to be used.
>>>>
>>>> One more thing that I would also change is that I don't think the
>>>> "plan" and "scan" endpoints make much sense. We refer to the "scan" portion
>>>> of this as "planFiles" in the reference implementation, and "scan" is used
>>>> for actually reading data. To be less confusing, I think that file scan
>>>> tasks should be returned by a "plan" endpoint and the manifest plan tasks
>>>> (or shards) should be returned by a "pre-plan" endpoint. Does anyone else
>>>> like the names "pre-plan" and "plan" better?
>>>>
>>>> Ryan
>>>>
>>>> On Mon, Jan 29, 2024 at 12:02 PM Chertara, Rahil
>>>> <rcher...@amazon.com.invalid> wrote:
>>>>
>>>>> Hi All hope everyone is doing well,
>>>>>
>>>>>
>>>>> Wanted to revive the discussion around the Rest Table Scan API work.
>>>>> For a refresher here is the original proposal:
>>>>> https://docs.google.com/document/d/1FdjCnFZM1fNtgyb9-v9fU4FwOX4An-pqEwSaJe8RgUg/edit#heading=h.cftjlkb2wh4h
>>>>> as well as the PR: https://github.com/apache/iceberg/pull/9252
>>>>>
>>>>>
>>>>> From the last messages on the thread, I believe Ryan and Jack were in
>>>>> favor of having two distinct api endpoints /plan and /scan, as well as a
>>>>> stricter json definition for the "shard”, here is an example below from
>>>>> what was discussed.
>>>>>
>>>>>
>>>>> *POST /v1/namespaces/ns/tables/t/plan *{ "filter": { "type": "in",
>>>>> "term": "x", "values": [1, 2, 3] }, "select": ["x", "a.b"]}
>>>>>
>>>>> { "manifest-plan-tasks": [
>>>>> { "start": 0, "length": 1000, "manifest": { "path":
>>>>> "s3://some/manifest.avro", ...}, "delete-manifests": [...] },
>>>>> { ... }
>>>>> ]}
>>>>>
>>>>>
>>>>> *POST /v1/namespaces/ns/tables/t/scan *{ "filter": {"type": "in",
>>>>> "term": "x", "values": [1, 2, 3] },
>>>>>
>>>>> "select": ["x", "a.b"],
>>>>> "manifest-plan-task": { "start": 0, "length": 1000, "manifest": {
>>>>> "path": "s3://some/manifest.avro", ...}, "delete-manifests": [...] } }
>>>>>
>>>>> { "file-scan-tasks": [...] }
>>>>>
>>>>>
>>>>> *POST /v1/namespaces/ns/tables/t/scan *{ "filter": {"type": "in",
>>>>> "term": "x", "values": [1, 2, 3] }, "select": ["x", "a.b"]}
>>>>>
>>>>>
>>>>> { "file-scan-tasks": [...] }
>>>>>
>>>>>
>>>>>
>>>>> However IIRC Micah and Renjie had some concerns around this stricter
>>>>> structure as this can make it harder to evolve in the future, as well as
>>>>> some potential scalability challenges for larger tables that have many
>>>>> manifest files. (Feel free to expand further on the concerns if my
>>>>> understanding is incorrect).
>>>>>
>>>>>
>>>>>
>>>>> Would appreciate if the community can leave any more thoughts/feedback
>>>>> on this thread, as well as on the google doc, and the PR.
>>>>>
>>>>>
>>>>>
>>>>> Regards,
>>>>> Rahil Chertara
>>>>>
>>>>>
>>>>>
>>>>> *From: *Renjie Liu <liurenjie2...@gmail.com>
>>>>> *Reply-To: *"dev@iceberg.apache.org" <dev@iceberg.apache.org>
>>>>> *Date: *Thursday, December 21, 2023 at 10:35 PM
>>>>> *To: *"dev@iceberg.apache.org" <dev@iceberg.apache.org>
>>>>> *Subject: *RE: [EXTERNAL] Proposal for REST APIs for Iceberg table
>>>>> scans
>>>>>
>>>>>
>>>>>
>>>>> *CAUTION*: This email originated from outside of the organization. Do
>>>>> not click links or open attachments unless you can confirm the sender and
>>>>> know the content is safe.
>>>>>
>>>>>
>>>>>
>>>>> I share the same concern with Micah. The shard detail should be
>>>>> implementation details of the server, rather than exposing directly to the
>>>>> client. If the goal is to make things stateless, we just need to attach a
>>>>> snapshot id + shard id, then a determined algorithm is supposed to give
>>>>> the
>>>>> same result. Also another concern is for huge analytics tables, we may
>>>>> have
>>>>> a lot of manifest files, which may lead to large traffic from the rest
>>>>> server.
>>>>>
>>>>>
>>>>>
>>>>> On Thu, Dec 21, 2023 at 7:41 AM Micah Kornfield <emkornfi...@gmail.com>
>>>>> wrote:
>>>>>
>>>>> Also +1 for having a more strict definition of the shard. Having
>>>>> arbitrary JSON was basically what we experimented with a string shard ID,
>>>>> and we ended up with something very similar to the manifest plan task you
>>>>> describe in the serialized ID string.
>>>>>
>>>>>
>>>>>
>>>>> IIUC the proposal correctly, I'd actually be -0.0 on the stricter
>>>>> structure. I think forcing a contract where it isn't strictly necessary
>>>>> makes it harder to evolve the system in the future. For example it makes
>>>>> it harder to address potential scalability problems in a transparent way
>>>>> (e.g. extreme edge cases in cardinality between manifest files and delete
>>>>> files).
>>>>>
>>>>>
>>>>>
>>>>> It also seems like it might overly constrain implementations (it is
>>>>> not clear we should need to compute the mapping between delete file
>>>>> manifests to data file manifests up front to start planning).
>>>>>
>>>>>
>>>>>
>>>>> On Tue, Dec 19, 2023 at 2:10 PM Jack Ye <yezhao...@gmail.com> wrote:
>>>>>
>>>>> +1 for having /plan and /scan, sounds like a good idea to separate
>>>>> those 2 distinct actions.
>>>>>
>>>>>
>>>>>
>>>>> Also +1 for having a more strict definition of the shard. Having
>>>>> arbitrary JSON was basically what we experimented with a string shard ID,
>>>>> and we ended up with something very similar to the manifest plan task you
>>>>> describe in the serialized ID string.
>>>>>
>>>>>
>>>>>
>>>>> So sounds like we are converging to the following APIs:
>>>>>
>>>>>
>>>>>
>>>>>
>>>>> *POST /v1/namespaces/ns/tables/t/plan *{ "filter": { "type": "in",
>>>>> "term": "x", "values": [1, 2, 3] }, "select": ["x", "a.b"]}
>>>>>
>>>>> { "manifest-plan-tasks": [
>>>>> { "start": 0, "length": 1000, "manifest": { "path":
>>>>> "s3://some/manifest.avro", ...}, "delete-manifests": [...] },
>>>>> { ... }
>>>>> ]}
>>>>>
>>>>>
>>>>> *POST /v1/namespaces/ns/tables/t/scan *{ "filter": {"type": "in",
>>>>> "term": "x", "values": [1, 2, 3] },
>>>>>
>>>>> "select": ["x", "a.b"],
>>>>> "manifest-plan-task": { "start": 0, "length": 1000, "manifest": {
>>>>> "path": "s3://some/manifest.avro", ...}, "delete-manifests": [...] } }
>>>>>
>>>>> { "file-scan-tasks": [...] }
>>>>>
>>>>>
>>>>> *POST /v1/namespaces/ns/tables/t/scan *{ "filter": {"type": "in",
>>>>> "term": "x", "values": [1, 2, 3] }, "select": ["x", "a.b"]}
>>>>>
>>>>>
>>>>> { "file-scan-tasks": [...] }
>>>>>
>>>>>
>>>>>
>>>>> If this sounds good overall, we can update the prototype to have more
>>>>> detailed discussions in code.
>>>>>
>>>>>
>>>>>
>>>>> -Jack
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>
>>>>> On Thu, Dec 14, 2023 at 6:10 PM Ryan Blue <b...@tabular.io> wrote:
>>>>>
>>>>> The tasks might look something like this:
>>>>>
>>>>>
>>>>>
>>>>> CombinedPlanTask
>>>>>
>>>>> - List<ManifestPlanTask>
>>>>>
>>>>>
>>>>>
>>>>> ManifestPlanTask
>>>>>
>>>>> - int start
>>>>>
>>>>> - int length
>>>>>
>>>>> - ManifestFile dataManifest
>>>>>
>>>>> - List<ManifestFile> deleteManifests
>>>>>
>>>>>
>>>>>
>>>>> On Thu, Dec 14, 2023 at 4:07 PM Ryan Blue <b...@tabular.io> wrote:
>>>>>
>>>>> Seems like that track has expired (This Internet-Draft will expire on
>>>>> 13 May 2022)
>>>>>
>>>>> Yeah, looks like we should just use POST. That’s too bad. QUERY seems
>>>>> like a good idea to me.
>>>>>
>>>>> Distinguish planning using shard or not
>>>>>
>>>>> I think this was a mistake on my part. I was still thinking that we
>>>>> would have a different endpoint for first-level planning to produce shards
>>>>> and the route to actually get files. Since both are POST requests with the
>>>>> same path (/v1/namespaces/ns/tables/t/scans) that no longer works.
>>>>> What about /v1/namespaces/ns/tables/t/scan and
>>>>> /v1/namespaces/ns/tables/t/plan? The latter could use some variant of
>>>>> planFiles since that’s what we are wrapping in the Java API.
>>>>>
>>>>> Necessity of scan ID
>>>>>
>>>>> Yes, I agree. If you have shard IDs then you don’t really need a scan
>>>>> ID. You could always have one internally but send it as part of the shard
>>>>> ID.
>>>>>
>>>>> Shape of shard payload
>>>>>
>>>>> I think we have 2 general options depending on how strict we want to
>>>>> be.
>>>>>
>>>>> 1. Require a standard shard definition
>>>>> 2. Allow arbitrary JSON and leave it to the service
>>>>>
>>>>> I lean toward the first option, which would be a data manifest and the
>>>>> associated delete manifests for the partition. We could also extend that
>>>>> to
>>>>> a group of manifests, each with a list of delete manifests. And we could
>>>>> also allow splitting to ensure tasks don’t get too large with big files.
>>>>> This all looks basically like FileScanTask, but with manifests and delete
>>>>> manifests.
>>>>>
>>>>>
>>>>>
>>>>> On Wed, Dec 13, 2023 at 4:39 PM Jack Ye <yezhao...@gmail.com> wrote:
>>>>>
>>>>> Seems like that track has expired (This Internet-Draft will expire on
>>>>> 13 May 2022), not sure how these RFCs are managed, but it does not seem
>>>>> hopeful to have this verb in. I think people are mostly using POST for
>>>>> this
>>>>> use case already.
>>>>>
>>>>>
>>>>>
>>>>> But overall I think we are in agreement with the general direction. A
>>>>> few detail discussions:
>>>>>
>>>>>
>>>>>
>>>>> *Distinguish planning using shard or not*
>>>>>
>>>>> Maybe we should add a query parameter like *distributed=true* to
>>>>> distinguish your first and third case, since they are now sharing the same
>>>>> signature. If the requester wants to use distributed planning, then some
>>>>> sharding strategy is provided as a response for the requester to send more
>>>>> detailed requests.
>>>>>
>>>>> *Necessity of scan ID*
>>>>> In this approach, is scan ID still required? Because the shard payload
>>>>> already fully describes the information to retrieve, it seems like we can
>>>>> just drop the *scan-id* query parameter in the second case. Seems
>>>>> like it's kept for the case if we still want to persist some state, but it
>>>>> seems like we can make a stateless style fully working.
>>>>>
>>>>> *Shape of shard payload*
>>>>> What do you think is necessary information of the shard payload? It
>>>>> seems like we need at least the location of the manifests, plus the delete
>>>>> manifests or delete files associated with the manifests. I like the idea
>>>>> of
>>>>> making it a "shard task" that is similar to a file scan task, and it might
>>>>> allow us to return a mixture of both types of tasks, so we can have better
>>>>> control of the response size.
>>>>>
>>>>> -Jack
>>>>>
>>>>>
>>>>>
>>>>> On Wed, Dec 13, 2023 at 3:50 PM Ryan Blue <b...@tabular.io> wrote:
>>>>>
>>>>> I just changed it to POST after looking into support for the QUERY
>>>>> method. It's a new HTTP method for cases like this where you don't want to
>>>>> pass everything through query params. Here's the QUERY method RFC
>>>>> <https://www.ietf.org/archive/id/draft-ietf-httpbis-safe-method-w-body-02.html>,
>>>>> but I guess it isn't finalized yet?
>>>>>
>>>>>
>>>>>
>>>>> Just read them like you would a POST request that doesn't actually
>>>>> create anything.
>>>>>
>>>>>
>>>>>
>>>>> On Wed, Dec 13, 2023 at 3:45 PM Jack Ye <yezhao...@gmail.com> wrote:
>>>>>
>>>>> Thanks, the Gist explains a lot of things. This is actually very close
>>>>> to our way of implementing the shard ID, we were defining the shard ID as
>>>>> a
>>>>> string, and the string content is actually something similar to the
>>>>> information of the JSON payload you showed, so we can persist minimum
>>>>> information in storage.
>>>>>
>>>>>
>>>>>
>>>>> Just one clarification needed for your Gist:
>>>>>
>>>>>
>>>>>
>>>>> > QUERY /v1/namespaces/ns/tables/t/scans?scan-id=1
>>>>>
>>>>>
>>>>>
>>>>> > { "shard": { "id": 1, "manifests": ["C"] }, "filter": {"type": "in",
>>>>> "term": "x", "values": [1, 2, 3] } }
>>>>>
>>>>>
>>>>>
>>>>> >
>>>>>
>>>>> > { "file-scan-tasks": [...] }
>>>>>
>>>>>
>>>>>
>>>>> Here, what does this QUERY verb mean? Is that a GET? If it's GET, we
>>>>> cannot have a request body. That's actually why we expressed that as an ID
>>>>> string, since we can put it as a query parameter.
>>>>>
>>>>>
>>>>>
>>>>> -Jack
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>
>>>>> On Wed, Dec 13, 2023 at 3:25 PM Ryan Blue <b...@tabular.io> wrote:
>>>>>
>>>>> Jack,
>>>>>
>>>>> It sounds like what I’m proposing isn’t quite clear because your
>>>>> initial response was arguing for a sharding capability. I agree that
>>>>> sharding is a good idea. I’m less confident about two points:
>>>>>
>>>>> 1. Requiring that the service is stateful. As Renjie pointed out,
>>>>> that makes it harder to scale the service.
>>>>> 2. The need for both pagination *and* sharding as separate things
>>>>>
>>>>> And I also think that Fokko has a good point about trying to keep
>>>>> things simple and not requiring the CreateScan endpoint.
>>>>>
>>>>> For the first point, I’m proposing that we still have a CreateScan
>>>>> endpoint, but instead of sending only a list of shard IDs it can also send
>>>>> either a standard shard “task” or an optional JSON definition. Let’s
>>>>> assume
>>>>> we can send arbitrary JSON for an example. Say I have a table with 4
>>>>> manifests, A through D and that C and D match some query filter. When
>>>>> I call the CreateScan endpoint, the service would send back tasks
>>>>> with that information: {"id": 1, "manifests": ["C"]}, {"id": 2,
>>>>> "manifests": ["D"]}. By sending what the shards mean (the manifests
>>>>> to read), my service can be stateless: any node can get a request for
>>>>> shard
>>>>> 1, read manifest C, and send back the resulting data files.
>>>>>
>>>>> I don’t see much of an argument against doing this *in principle*. It
>>>>> gives you the flexibility to store state if you choose or to send state to
>>>>> the client for it to pass back when calling the GetTasks endpoint.
>>>>> There is a practical problem, which is that it’s annoying to send a GET
>>>>> request with a JSON payload because you can’t send a request body. It’s
>>>>> probably obvious, but I’m also not a REST purist so I’d be fine using POST
>>>>> or QUERY for this. It would look something like this Gist
>>>>> <https://gist.github.com/rdblue/d2b65bd2ad20f85ee9d04ccf19ac8aba>.
>>>>>
>>>>> In your last reply, you also asked whether a stateless service is a
>>>>> goal. I don’t think that it is, but if we can make simple changes to the
>>>>> spec to allow more flexibility on the server side, I think that’s a good
>>>>> direction. You also asked about a reference implementation and I consider
>>>>> CatalogHandlers
>>>>> <https://github.com/apache/iceberg/blob/main/core/src/main/java/org/apache/iceberg/rest/CatalogHandlers.java>
>>>>> to be that reference. It does everything except for the work done by your
>>>>> choice of web application framework. It isn’t stateless, but it only
>>>>> relies
>>>>> on a Catalog implementation for persistence.
>>>>>
>>>>> For the second point, I don’t understand why we need both sharding and
>>>>> pagination. That is, if we have a protocol that allows sharding, why is
>>>>> pagination also needed? From my naive perspective on how sharding would
>>>>> work, we should be able to use metadata from the manifest list to limit
>>>>> the
>>>>> potential number of data files in a given shard. As long as we can limit
>>>>> the size of a shard to produce more, pagination seems like unnecessary
>>>>> complication.
>>>>>
>>>>> Lastly, for Fokko’s point, I think another easy extension to the
>>>>> proposal is to support a direct call to GetTasks. There’s a trade-off
>>>>> here, but if you’re already sending the original filter along with the
>>>>> request (in order to filter records from manifest C for instance)
>>>>> then the request is already something the protocol can express. There’s an
>>>>> objection concerning resource consumption on the service and creating
>>>>> responses that are too large or take too long, but we can get around that
>>>>> by responding with a code that instructs the client to use the
>>>>> CreateScan API like 413 (Payload too large). I think that would allow
>>>>> simple clients to function for all but really large tables. The gist above
>>>>> also shows what this might look like.
>>>>>
>>>>> Ryan
>>>>>
>>>>>
>>>>>
>>>>> On Wed, Dec 13, 2023 at 11:53 AM Jack Ye <yezhao...@gmail.com> wrote:
>>>>>
>>>>> The current proposal definitely makes the server stateful. In our
>>>>> prototype we used other components like DynamoDB to keep track of states.
>>>>> If keeping it stateless is a tenant we can definitely make the proposal
>>>>> closer to that direction. Maybe one thing to make sure is, is this a core
>>>>> tenant of the REST spec? Today we do not even have an official reference
>>>>> implementation of the REST server, I feel it is hard to say what are the
>>>>> core tenants. Maybe we should create one?
>>>>>
>>>>>
>>>>>
>>>>> Pagination is a common issue in the REST spec. We also see similar
>>>>> limitations with other APIs like GetTables, GetNamespaces. When a catalog
>>>>> has many namespaces and tables it suffers from the same issue. It is also
>>>>> not ideal for use cases like web browsers, since typically you display a
>>>>> small page of results and do not need the full list immediately. So I feel
>>>>> we cannot really avoid some state to be kept for those use cases.
>>>>>
>>>>>
>>>>>
>>>>> Chunked response might be a good way to work around it. We also
>>>>> thought about using HTTP2. However, these options seem to be not very
>>>>> compatible with OpenAPI. We can do some further research in this domain,
>>>>> would really appreciate it if anyone has more insights and experience with
>>>>> OpenAPI that can provide some suggestions.
>>>>>
>>>>>
>>>>>
>>>>> -Jack
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>
>>>>> On Tue, Dec 12, 2023 at 6:21 PM Renjie Liu <liurenjie2...@gmail.com>
>>>>> wrote:
>>>>>
>>>>> Hi, Rahi and Jack:
>>>>>
>>>>> Thanks for raising this.
>>>>>
>>>>>
>>>>>
>>>>> My question is that the pagination and sharding will make the rest
>>>>> server stateful, e.g. a sequence of calls is required to go to the same
>>>>> server. In this case, how do we ensure the scalability of the rest server?
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>
>>>>> On Wed, Dec 13, 2023 at 4:09 AM Fokko Driesprong <fo...@apache.org>
>>>>> wrote:
>>>>>
>>>>> Hey Rahil and Jack,
>>>>>
>>>>>
>>>>>
>>>>> Thanks for bringing this up. Ryan and I also discussed this briefly in
>>>>> the early days of PyIceberg and it would have helped a lot in the speed of
>>>>> development. We went for the traditional approach because that would also
>>>>> support all the other catalogs, but now that the REST catalog is taking
>>>>> off, I think it still makes a lot of sense to get it in.
>>>>>
>>>>>
>>>>>
>>>>> I do share the concern raised Ryan around the concepts of shards and
>>>>> pagination. For PyIceberg (but also for Go, Rust, and DuckDB) that are
>>>>> living in a single process today the concept of shards doesn't add value.
>>>>> I
>>>>> see your concern with long-running jobs, but for the non-distributed
>>>>> cases,
>>>>> it will add additional complexity.
>>>>>
>>>>>
>>>>>
>>>>> Some suggestions that come to mind:
>>>>>
>>>>> - Stream the tasks directly back using a chunked
>>>>> response, reducing the latency to the first task. This would also solve
>>>>> things with the pagination. The only downside I can think of is having
>>>>> delete files where you first need to make sure there are deletes
>>>>> relevant
>>>>> to the task, this might increase latency to the first task.
>>>>> - Making the sharding optional. If you want to shard you call the
>>>>> CreateScan first and then call the GetScanTask with the IDs. If you
>>>>> don't
>>>>> want to shard, you omit the shard parameter and fetch the tasks
>>>>> directly
>>>>> (here we need also replace the scan string with the full
>>>>> column/expression/snapshot-id etc).
>>>>>
>>>>> Looking forward to discussing this tomorrow in the community sync
>>>>> <https://iceberg.apache.org/community/#iceberg-community-events>!
>>>>>
>>>>>
>>>>>
>>>>> Kind regards,
>>>>>
>>>>> Fokko
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>
>>>>> Op ma 11 dec 2023 om 19:05 schreef Jack Ye <yezhao...@gmail.com>:
>>>>>
>>>>> Hi Ryan, thanks for the feedback!
>>>>>
>>>>>
>>>>>
>>>>> I was a part of this design discussion internally and can provide more
>>>>> details. One reason for separating the CreateScan operation was to make
>>>>> the
>>>>> API asynchronous and thus keep HTTP communications short. Consider the
>>>>> case
>>>>> where we only have GetScanTasks API, and there is no shard specified. It
>>>>> might take tens of seconds, or even minutes to read through all the
>>>>> manifest list and manifests before being able to return anything. This
>>>>> means the HTTP connection has to remain open during that period, which is
>>>>> not really a good practice in general (consider connection failure, load
>>>>> balancer and proxy load, etc.). And when we shift the API to asynchronous,
>>>>> it basically becomes something like the proposal, where a stateful ID is
>>>>> generated to be able to immediately return back to the client, and the
>>>>> client get results by referencing the ID. So in our current prototype
>>>>> implementation we are actually keeping this ID and the whole REST service
>>>>> is stateful.
>>>>>
>>>>>
>>>>>
>>>>> There were some thoughts we had about the possibility to define a
>>>>> "shard ID generator" protocol: basically the client agrees with the
>>>>> service
>>>>> a way to deterministically generate shard IDs, and service uses it to
>>>>> create shards. That sounds like what you are suggesting here, and it
>>>>> pushes
>>>>> the responsibility to the client side to determine the parallelism. But in
>>>>> some bad cases (e.g. there are many delete files and we need to read all
>>>>> those in each shard to apply filters), it seems like there might still be
>>>>> the long open connection issue above. What is your thought on that?
>>>>>
>>>>>
>>>>>
>>>>> -Jack
>>>>>
>>>>>
>>>>>
>>>>> On Sun, Dec 10, 2023 at 10:27 AM Ryan Blue <b...@tabular.io> wrote:
>>>>>
>>>>> Rahil, thanks for working on this. It has some really good ideas that
>>>>> we hadn't considered before like a way for the service to plan how to
>>>>> break
>>>>> up the work of scan planning. I really like that idea because it makes it
>>>>> much easier for the service to keep memory consumption low across
>>>>> requests.
>>>>>
>>>>>
>>>>>
>>>>> My primary feedback is that I think it's a little too complicated
>>>>> (with both sharding and pagination) and could be modified slightly so that
>>>>> the service doesn't need to be stateful. If the service isn't necessarily
>>>>> stateful then it should be easier to build implementations.
>>>>>
>>>>>
>>>>>
>>>>> To make it possible for the service to be stateless, I'm proposing
>>>>> that rather than creating shard IDs that are tracked by the service, the
>>>>> information for a shard can be sent to the client. My assumption here is
>>>>> that most implementations would create shards by reading the manifest
>>>>> list,
>>>>> filtering on partition ranges, and creating a shard for some reasonable
>>>>> size of manifest content. For example, if a table has 100MB of metadata in
>>>>> 25 manifests that are about 4 MB each, then it might create 9 shards with
>>>>> 1-4 manifests each. The service could send those shards to the client as a
>>>>> list of manifests to read and the client could send the shard information
>>>>> back to the service to get the data files in each shard (along with the
>>>>> original filter).
>>>>>
>>>>>
>>>>>
>>>>> There's a slight trade-off that the protocol needs to define how to
>>>>> break the work into shards. I'm interested in hearing if that would work
>>>>> with how you were planning on building the service on your end. Another
>>>>> option is to let the service send back arbitrary JSON that would get
>>>>> returned for each shard. Either way, I like that this would make it so the
>>>>> service doesn't need to persist anything. We could also make it so that
>>>>> small tables don't require multiple requests. For example, a client could
>>>>> call the route to get file tasks with just a filter.
>>>>>
>>>>>
>>>>>
>>>>> What do you think?
>>>>>
>>>>>
>>>>>
>>>>> Ryan
>>>>>
>>>>>
>>>>>
>>>>> On Fri, Dec 8, 2023 at 10:41 AM Chertara, Rahil
>>>>> <rcher...@amazon.com.invalid> wrote:
>>>>>
>>>>> Hi all,
>>>>>
>>>>> My name is Rahil Chertara, and I’m a part of the Iceberg team at
>>>>> Amazon EMR and Athena. I’m reaching out to share a proposal for a new Scan
>>>>> API that will be utilized by the RESTCatalog. The process for table scan
>>>>> planning is currently done within client engines such as Apache Spark. By
>>>>> moving scan functionality to the RESTCatalog, we can integrate Iceberg
>>>>> table scans with external services, which can lead to several benefits.
>>>>>
>>>>> For example, we can leverage caching and indexes on the server side to
>>>>> improve planning performance. Furthermore, by moving this scan logic to
>>>>> the
>>>>> RESTCatalog, non-JVM engines can integrate more easily. This all can be
>>>>> found in the detailed proposal below. Feel free to comment, and add your
>>>>> suggestions .
>>>>>
>>>>> Detailed proposal:
>>>>> https://docs.google.com/document/d/1FdjCnFZM1fNtgyb9-v9fU4FwOX4An-pqEwSaJe8RgUg/edit#heading=h.cftjlkb2wh4h
>>>>>
>>>>> Github POC: https://github.com/apache/iceberg/pull/9252
>>>>>
>>>>> Regards,
>>>>>
>>>>> Rahil Chertara
>>>>> Amazon EMR & Athena
>>>>> rcher...@amazon.com
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>
>>>>> --
>>>>>
>>>>> Ryan Blue
>>>>>
>>>>> Tabular
>>>>>
>>>>>
>>>>>
>>>>>
>>>>> --
>>>>>
>>>>> Ryan Blue
>>>>>
>>>>> Tabular
>>>>>
>>>>>
>>>>>
>>>>>
>>>>> --
>>>>>
>>>>> Ryan Blue
>>>>>
>>>>> Tabular
>>>>>
>>>>>
>>>>>
>>>>>
>>>>> --
>>>>>
>>>>> Ryan Blue
>>>>>
>>>>> Tabular
>>>>>
>>>>>
>>>>>
>>>>>
>>>>> --
>>>>>
>>>>> Ryan Blue
>>>>>
>>>>> Tabular
>>>>>
>>>>>
>>>>
>>>> --
>>>> Ryan Blue
>>>> Tabular
>>>>
>>>
--
Ryan Blue
Tabular
